Twll Maen Grisial
Fron Olau, Prenteg, Dolbenmaen, Gwynedd, Wales, UK
A mineralogical locale near Prenteg, probably best known for being the type locality of Brookite.
Mindat lists 16 mineral species from the site, including one for which it is the type locality – Brookite.
Other titanium minerals are found here too – anatase, ilmenite, rutile, titanite.
The site is probably best known amongst micro collectors, as anatase and brookite specimens from the site can be really rather nice – if a little small.
The site now appears to be inaccessible, with the researchgate publication linked below suggesting this is to prevent rockfalls onto the A498.
Further reading
- https://www.mindat.org/loc-4279.html
- https://www.researchgate.net/publication/307932242_Rock_Crystal_Mining_in_Wales
- https://www.mineralienatlas.de/lexikon/index.php/UK/Wales/Gwynedd%2C%20County/Prenteg/Fron%20Olau/Twll%20Maen%20Grisial
We do have stock from various locales around Gwynedd, including:
Gwynedd, Wales- Benallt Mine, Rhiw, Aberdaron, Gwynedd, Wales
- Dorothea Quarry, Llanllyfni, Gwynedd, Wales
- Llechog Ridge, Snowdonia National Park, Gwynedd, Wales
- Manod Quarry, Ffestiniog, Gwynedd, Wales
- Tanygrisiau Railway Station, Tanygrisiau, Ffestiniog, Gwynedd, Wales
- Twll Maen Grisial, Fron Olau, Prenteg, Dolbenmaen, Gwynedd, Wales
If you’d like to view another county, use the following links: • Bridgend • Caerphilly • Cardiff • Ceredigion • Clwyd • Conwy • Flintshire • Gwynedd • Isle of Anglesey • Powys • Rhondda Cynon Taf • Vale of Glamorgan •
For the rest of our UK stock, see
United Kingdom
Fossils from the United Kingdom - Minerals from the United Kingdom